The invention relates to devices which use mechanical energy for cooling and heating purposes, and in particular to improvements in reciprocal bellows type evaporative cooling systems and heat pumps. An objective of the present invention is to provide a bellows type cooling and heating system which uses less force and energy than standard bellows temperature changing systems. Another objective of the present invention is to provide a cooling system which can use water instead of freon. Another objective is to provide cooling and heating systems which are adapted to operate under low refrigerant pressures, and low temperature differentials between the heat source and the heat sink. Another objective of the present invention is to provide an expander-compressor which is especially adapted to miniature cooling and heating devices, such as those which can be used in micro-climate cooling and heating systems. Another objective is to provide a force and energy sparing transmission of movement between an air evacuated enclosure and the atmosphere.
All compressor type evaporative temperature systems consist of 1. a low boiling point liquid used as a refrigerant and 2. the components involved in the generation and transmission of mechanical energy to compress and expand the vapors of the refrigerant. Most standard compressor type cooling systems use chlorinated hydrocarbons as low boiling point refrigerants (freons). The freons are hazardous because they damage the atmospheric ozone layer.
The boiling point of water can be lowered to freezing temperatures by an air vacuum. Under an air vacuum the water can, therefore, function as a low boiling point refrigerant. Water has several advantages over freon. It is non-toxic to the environment. it is cheaper than freon, and its latent heat of vaporization is higher than that of freon. In addition to the above, water operates at lower pressures and at lower pressure differentials (between the relatively cold and relatively hot portions of the compression types cooling and heating systems) than freons. They therefore require less force to operate than freon based systems. The main disadvantage of using water as a low boiling point refrigerant is the fact that the lowering of the boiling point of the water requires an air vacuum. This requires the housing of the water in a chamber from which the air has been evacuated. Mechanical force must then be transmitted to the water vapors through the walls of the chamber enclosing the air vacuum. Force transmitting means which pierce the surface of the air evacuated chamber increase the chances of leakage of air into the chamber and cancellation of the air vacuum. The most convenient force transmitting means which do not pierce the surface consist of bellows walls which increase and decrease the volume of the chamber. This requires a moving bellows wall surface which is exposed in its inner side to the vacuum and in its outer side to the atmosphere, This requires an investment of power to overcome atmospheric pressure upon the outside of the moving wall during the expansion phase of the reciprocal movements of the wall. The present invention provides means whereby atmospheric resistance to the movement of the wall is overcome without the investment of man made energy sources.
The invention is based upon the fact that force follows the path of least resistance. The direction of any force can, therefore, be controlled by the regulation of the resistance to the flow of the force. In the present invention an atmospheric force, or a vapor force, which provides a resistance to the movement of the movable wall of a bellows chamber, is balanced and neutralized by an atmospheric force, or a vapor force, which is made to flow in the opposite direction. Electric power is, therefore, not required to overcome the resistances. Since work is equal to force times displacement the present invention uses less electric energy to obtain a given displacement than conventional bellows compressor systems, when the temperatures and the refrigerants in the devices are identical.
In addition to the above, the fact that the position of the movable walls of the compressor expander can be changed by a tipping of a balance of opposing forces, causes the moving walls to be responsive to very small outside forces. The balanced bellows compressor-expander is, therefore, responsive to lower pressure ranges than single standard bellows compressors (see numerical example).